galaxy environments

I had a long talk with Chuck Steidel (Caltech) today in which we ranged over many topics, but in particular we discussed the best evidence that galaxies can and do interact with their large-scale environments, by, eg, driving massive outflows with star-formation events. Chuck pointed out that there are four times as many metal (in astronomical parlance: elements beyond helium) atoms outside galaxies as inside, so in addition to his direct evidence for outflows, there is a pretty strong indirect argument.

I gave an informal lunch talk to the galaxy-interested denizens of the Spitzer Science Center on what we know about galaxy environments from the Sloan Digital Sky Survey and related data.